The applicant claims and requests a foreign priority, through the Paris Convention for the Protection of Industry Property, based on a patent application filed in the Republic of Korea (South Korea) with the filing date of Nov. 21, 2000, with the patent application No. 10-2000-0069219, by the applicant. (See the Attached Declaration)
The present invention relates to coil windings for electrically powered motors. More specifically, this invention relates to an improved method of winding coils for electric motors, generators and alternators to substantially simplify and expedite the coil windings.
As is conventionally known, a brushless motor adopting alternating current (AC) and direct current (DC) has an outer stator surrounding an inner rotor in which the rotor is provided to rotate within the stator.
In most electric motors, the stator includes a number of regularly spaced radially oriented teeth along its inner periphery, which define a corresponding number of slots. The teeth and slots extend along the entire axial length of the stator. Through various techniques which are well known to those skilled in the field, electrical windings are positioned in the slots between the teeth from one end of the stator to another, and around the teeth at the opposite ends of the stator. In this manner, the electrical windings are precisely oriented with respect to the rotor so that AC or switched DC voltage applied to the windings will induce a magnetic field which has a known, predetermined orientation. The electro-magnetic field is designed to react with permanent magnets or inductive windings on the rotor to turn the rotor in a desired direction.
It can be difficult and time consuming to install the electrical windings into a slotted stator, and a fair amount of complicated machinery has been developed over the years to do this. In addition to the manufacturing difficulties presented by the slotted stator configuration, the presence of the teeth which define the slots creates magnetic discontinuities, which can affect the efficiency of the motor. In addition, the presence of the teeth limits the number of windings which can be positioned in the critical area of the stator adjacent to the rotor. This also adversely affects the efficiency of the motor. If the entire area on the stator which is adjacent to the rotor could be filled with conductors, motor efficiency would increase, and losses due to factors such as hysteresis would be lessened.
U.S. Pat. No. 5,197,180 discloses a method of improving a motor efficiency by securing effective conductors that a motor requires, by filling the entire area of the stator with coils to thereby decrease losses caused by hysterisis.
Referring to FIG. 1 shown herewith, U.S. Pat. No. 5,197,180 provides a mandrel 1 with a hexagonal outer formation. Three coils 2 are wound around the mandrel 1 and the mandrel is removed from the wound coil formation which is then flattened to form a flat two-layered web 2xe2x80x2. Then, the flat web 2xe2x80x2 is rolled end-to-end to form a circular shape which can be inserted into a motor and at the same time allow a rotor to be inserted thereinto.
However, the cited coil winding method may incur defectives in the course of coil winding and forming the two-layered flat web, and disadvantageously requires precision devices to prevent incurrence of the defectives. That is, when flattening the coil wound formation to form the flat web 2xe2x80x2, the coils 2 may lose an even alignment thereof and be tangled, resulting in critical effect on the motor performance. Further, in the course of rolling the flat web 2 to form the circular shape there is additionally required an extra device and process for adjusting radial measurements of the circular shape to a target size in accordance to a motor, thereby increasing production cost while damaging production efficiency.
The invention is contrived to overcome the conventional disadvantages. Therefore, it is an object of the present invention to provide a coil winding method for realizing a coil-wound article in a cylindrical formation which is applicable to a stator without deformation of the coil-wound article. Another object is to provide a coil winding method for implementing a high efficiency motor while substantially decreasing production costs and defective rates.
To achieve the above-described objects, a method of forming a coil-wound article for an electric motor, an electric generator, or an electric alternator, according to the present invention, comprises the steps of: winding a first coil by a predetermined number of laps clockwise around a first swath, counterclockwise around a second swath, and clockwise around a third swath of a plurality of hooks correspondingly provided out of a plurality of slots formed along an outer periphery of a mandrel, wherein the hooks are collapsibly protruded from within the mandrel through the slots, wherein the hooks are consecutively grouped into the first, second and third swaths, wherein said each swath at least includes a first hook, a second hook and a third hook; winding a second coil by a predetermined number of laps clockwise around from between the first and second hooks of the first swath to between the first and second hooks of the second swath, counterclockwise around from between the first and second hooks of the second swath to between the first and second hooks of the third swath, and clockwise around from between the first and second hooks of the third swath to between the first and second hooks of the first swath; winding a third coil by a predetermined number of laps clockwise around from between the second and third hooks of the first swath to between the second and third hooks of the second swath, counterclockwise around from between the second and third hooks of the second swath to between the second and third hooks of the third swath, and clockwise around from between the second and third hooks of the third swath to between the second and third hooks of the first swath; and releasing the wound first, second and third coils axially from the mandrel by collapsing the hooks below the outer periphery of the mandrel, thereby forming the coil-wound article.
In a preferred version, there are provided four swaths each having a first to fourth hook, wherein the first step further includes winding counterclockwise a fourth swath of a plurality of hooks correspondingly provided out of a plurality of slots formed along an outer periphery of a mandrel so that the hooks are collapsibly protruded from within the mandrel through the slots, and consecutively grouped into the first, second, third, and fourth swaths.
The method makes intermittent angular rotations either by 120 degrees in case of three swaths each having three hooks or by 90 degrees in case of four swaths each having three hook, in the first, second and third steps so that said each coil winding can be implemented from a single direction.
The advantages of the invention are numerous in that: (1) the coil winding method innovatively simplifies the steps required for forming the coil-wound article applicable to a stator for a motor such as brushless electric motors by substantially disregarding the conventionally required steps, that is, the present invention eliminates the conventional steps for flattening or rolling the coil-wound article; (2) because the simplified coil winding steps are realized by simply releasing the completed coil-wound article from the mandrel and without deformation of the coil-wound article, the coil-wound method of the invention substantially improves production efficiency while significantly decreasing effective rates; and (3) the coil-wound article completed and released from the cylindrical mandrel can be directly assembled to a target stator without requiring adjustment of radius measurements to the target stator, thereby improving productivity for fabricating the coil-wound article and stabilizing magnetic inductivity for the applied stator.
Although the present invention is briefly summarized, the fuller understanding of the invention can be obtained by the following drawings, detailed description and appended claims.